Image forming apparatus and image forming method

ABSTRACT

In an initializing process at a time of switch-on, a scanner CPU sends an initialization command request to a system CPU. Upon receiving the initialization command request from the scanner CPU, the system CPU sends an initialization command to the scanner CPU. The scanner CPU, which has received the initialization command, executes an initializing process. When the initialization is completed, the scanner CPU informs the system CPU of the completion of initialization. After the system CPU is informed of the completion of initialization from all sub-control units (including a printer CPU and a panel CPU in the embodiment), the system CPU instructs an LCD to display “Ready” and enters a standby state.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to an image forming apparatus such as adigital copying machine, which has a scanner section, a printer sectionand a control panel, reads an image on an original and forms an image,and to an image forming method.

2. Description of the Related Art

In the prior art, there is known an image forming apparatus such as adigital copying machine, which comprises a single main control unit thatexecutes an overall control, and a plurality of sub-control units thatcontrol individual sections (scanner section, printer section, etc.) inaccordance with instructions from the main control unit. In this imageforming apparatus, when power is switched on, the plural sub-controlunits start execution of initialization upon receiving initializationinstructions from the main control unit that executes an overallcontrol.

In the system in which the sub-control units execute initialization uponreceiving initialization instructions from the main control unit,however, it is likely that the sub-control units are erroneously resetby noise, etc. In such a case, the sub-control units wait forinitialization instructions from the main control unit, similarly withthe time of switch-on. On the other hand, the main control unit does notrecognize the reset of the sub-control units, and thus the main controlunit does not send initialization instructions to the reset sub-controlunits. Consequently, matching between the main control unit andsub-control units is lost, leading to a control error. Hence, a processfor re-switching on, etc. is required.

BRIEF SUMMARY OF THE INVENTION

The object of an aspect of the present invention is to provide an imageforming apparatus and an image forming method, which can establishmatching between a main control unit and sub-control units, therebypreventing a control error process.

According to an aspect of the present invention, there is provided animage forming apparatus that reads an image on an original and forms animage, comprising: a plurality of sub-control means for controlling aplurality of units that constitute the apparatus; and main control meansfor controlling the plurality of sub-control means and controlling aninitialization command to the sub-control means on the basis of aninitialization command request from each of the sub-control means.

According to another aspect of the present invention, there is providedan image forming method for an image forming apparatus that reads animage on an original and forms an image, comprising: providing singlemain control means for executing an overall control of the apparatus,and a plurality of sub-control means for controlling a plurality ofunits that constitute the apparatus in accordance with an instructionfrom the main control means; and controlling an initialization commandto the sub-control means on the basis of an initialization commandrequest from each of the sub-control means.

Additional objects and advantages of an aspect of the invention will beset forth in the description which follows, and in part will be obviousfrom the description, or may be learned by practice of the invention.The objects and advantages of an aspect of the invention may be realizedand obtained by means of the instrumentalities and combinationsparticularly pointed out hereinafter.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING

The accompanying drawings, which are incorporated in and constitute apart of the specification, illustrate presently preferred embodiments ofthe invention, and together with the general description given above andthe detailed description of the embodiments given below, serve toexplain the principles of an aspect of the invention.

FIG. 1 is a block diagram that schematically shows the structure of animage forming apparatus according to an embodiment of the presentinvention;

FIG. 2 shows an internal structure of a system CPU;

FIG. 3 shows an internal structure of a page memory controller;

FIG. 4 is a view for explaining a PM-COM; and

FIG. 5 is a view for explaining an initializing operation in theembodiment.

DETAILED DESCRIPTION OF THE INVENTION

An embodiment of the present invention will now be described withreference to the accompanying drawings.

FIG. 1 schematically shows the structure of an image forming apparatus(digital plain-paper copier (DPPC)) according to the embodiment of theinvention.

The image forming apparatus comprises a system control unit 1 thatexecutes an overall control, a sub-scanner system 2 that converts imagedata on an original to a digital signal and inputs the digital signal, aprinter sub-system 4 that prints out the image data of the digitalsignal on paper, and a control panel 7 through which a user executesinput operations.

The system control unit 1 comprises a system CPU 10, a ROM 11, a mainmemory (SDRAM) 12, an NVRAM 14, a page memory control unit 30, a LANcontroller 60, and an HDD block 80. The ROM 11, main memory 12 and NVRAM14 are connected to the system CPU 10 via a local bus 15. In addition,the page memory control unit 30, LAN controller 60 and HDD block 80 areconnected to the system CPU 10 via a system bus 9.

The system CPU 10 controls the entirety of the apparatus.

The ROM 11 stores a control program for controlling the entirety of theapparatus.

The main memory 12 comprises a volatile DRAM that is loaded with thecontrol program by the system CPU 10 at the time of power-on. Thecontrol program is run in the power-on state.

The NVRAM 14 is backed up by a battery, and stores setting valuesassociated with the machine.

The page memory control unit 30 temporarily stores page-unit image dataof a digital signal. The page memory control unit 30 comprises a pagememory (SDRAM) 300 that temporarily stores page-unit image data, and apage memory controller 301 that controls the page memory 300.

The HDD block 80 can store a plurality of image data. The HDD block 80comprises a hard disk drive (HDD) 830 and an IDE controller 800 servingas an interface with the system bus 9.

The LAN controller 60 controls transmission/reception of image databetween a personal computer (not shown), which is connected to thenetwork, and the image forming apparatus.

The system control unit 1, as shown in FIG. 1, comprises two circuitboards, i.e. a system control circuit 5 and the HDD block 80.

The system control circuit 5 comprises the system CPU 10, ROM 11, mainmemory 12, NVRAM 14, local bus 15, page memory control unit 30, LANcontroller 60 and system bus 9.

The scanner sub-system 2 comprises a CCD 201, a scanner image processing202, and a scanner CPU 203. The scanner sub-system 2 also includes anoriginal convey unit (not shown) that conveys an original at apredetermined timing.

The CCD 201 optically reads an original on a line-by-line basis in syncwith the conveyance of the original, and converts the read image data toan electric signal.

The scanner image processing 202 converts the electric signal, which isoutput from the CCD 201, to 8-bit/pixel data, and executes an imageprocess corresponding to a designated image mode such as a charactermode, a character/photo mode or a photo mode. Then, the scanner imageprocessing 202 executes a tone process to produce 1-bit/pixel data. Thescanner image processing 202 outputs the tone-processed image data at apredetermined timing to the page memory control unit 3 via a scannerimage I/F 92.

The scanner CPU 203 controls the scanner sub-system 2.

The printer sub-system 4 comprises a printer image processing 41, alaser drive 42, a printer CPU 43 and an image forming unit 44.

The printer image processing 41 reads out the image data, which istemporarily stored in the page memory 300, via a printer image I/F 91 ata predetermined timing, and executes an image process for the read-outimage data in the designated mode.

The laser drive 42 converts the image data, which is output from theprinter image processing 41, to image data.

The printer CPU 43 controls the printer sub-system 4.

The image forming unit 44 forms an image by an electrostatic recordingmethod on the basis of an optical signal from the laser drive 42,transfers the image to prescribed paper, and output the paper.

The control panel 7 comprises an LCD 70 that displays the state of themachine and various parameter information, a touch panel 71 that isdisposed on the LCD 70, numeral keys 72, a plurality of LEDs 73, and apanel CPU 74 that controls the control panel.

In the above-described configuration, the main control unit is thesystem CPU 10 of the system control unit 1, and the sub-control unitsare the scanner CPU 203 of the scanner sub-system 2, the printer CPU 43of the printer sub-system 4 and the panel CPU 74 of the control panel 7.

FIG. 2 shows an internal structure of the system CPU 10.

The system CPU 10 comprises a CPU core 100, a DRAM controller 101, a ROMcontroller 102, a local bus I/F 103, an interrupt controller 104, aserial I/O 105, a system bus controller 106, a timer 107, and aninternal bus 108.

The CPU core 100 executes the control program.

The DRAM controller 101 controls the main memory (SDRAM) 12 on the localbus 15.

The ROM controller 102 controls the ROM 11 and NVRAM 14 on the local bus15.

The local bus I/F 103 interfaces the local bus 15 with the DRAMcontroller 101 and ROM controller 102.

The interrupt controller 104 receives interrupts from the blocks in theapparatus, and notifies the CPU core 100 of a single interrupt on thebasis of a predetermined order of priority.

The serial I/O 105 functions as an interface for communication betweenthe scanner CPU 203, printer CPU 43, control panel CPU 74 and system CPUcore 100. The serial I/O 105 has a 3-channel configuration.

The system bus controller 106, as will be described later in detail,functions as an interface between the respective blocks on the systembus 9 and the respective blocks on the system control unit 1.

The internal bus 108 interconnects the CPU core 100, DRAM controller101, ROM controller 102, interrupt controller 104, 3-channel serial I/O105, system bus controller 106, and timer 107.

FIG. 3 shows an internal structure of the page memory controller 301.

The page memory controller 301 comprises a system bus I/F 32, an LCDcontroller 33, an LED controller 34 and a PM-CON 35.

The system bus I/F 32 functions as an interface between the respectiveinternal blocks and the system bus 9.

The PM-CON 35 controls the system bus I/F 32, LCD controller 33, LEDcontroller 34 and page memory 300. Further, the PM-CON 35 controls imagedata transfer between the page memory 300 and the devices (to bedescribed later) on the system bus 9, the scanner sub-unit 2 connectedvia the scanner image I/F 92, and the printer sub-unit 4 connected viathe printer image I/F 91.

The PM-CON 35 mediates access requests from the devices that access thepage memory 300 on the basis of a predetermined order of priority, andsuccessively accesses the page memory 300 in accordance with the accessrequests.

The devices that access the page memory 300 include the scanner imageprocessing 202, printer image processing 41, system CPU 10, LCDcontroller 33 and IDE controller 800.

The scanner image processing 202 writes image data into the page memory300 via the scanner image I/F 92.

The printer image processing 41 reads out image data from the pagememory 300 via the printer image I/F 91.

The IDE controller 800 stores image data, which is present in the pagememory 300, into the HDD 830, or restores image data from the HDD 830into the page memory 300.

The page memory 300 includes an area for temporarily storing image data,and a display data area for storing display data that is to be displayedon the LCD 70. The LCD controller 33 periodically reads out display datafrom the display data area of the page memory 300, and outputs thedisplay data to the LCD 70 in sync with a sync signal that is outputfrom the LCD 70 of the control panel 7. The LCD 70 successively displaysthe display data.

Next, the PM-CON 35 that controls the page memory 300 is describedreferring to FIG. 4.

The PM-CON 35 comprises a PDRAM control unit 36, a transfer channel 37,a data process block 38, and an address generator 39.

The transfer channel 37 functions as an interface of data transferbetween the page memory 300 and other process blocks. The transferchannel 37 comprises a scanner I/F 3501, a printer I/F 3509, an HDDtransfer (ch0) 3504, an HDD transfer (ch1) 3506, a compression (input)channel 3502, a compression (output) channel 3503, a decompression(input) channel 3507, a decompression (output) channel 3508, a memoryclear 3510, a CPU I/F 3511, and an LCD I/F 3512.

The data process block 38 comprises a compression process unit 3530, adecompression process unit 3531 and a rotation process unit 3532.

The address generator 39 generates addresses in the page memory 300 forrespective channels. The address generator 39 comprises an addressgeneration channel AGC (ch0) 3520, AGC (ch1) 3521, AGC (ch2) 3522, AGC(ch3) 3523, AGC (ch4) 3524, AGC (ch5) 3525, FIFO (ch0-A) 3526, FIFO(ch0-B) 3527, FIFO (ch1-A) 3528 and FIFO (ch1-B) 3529.

The scanner I/F 3501 receives, e.g. 8-pixel unit image data from thescanner sub-system 2 in sync with a sync signal that is output from thescanner sub-system 2. When the scanner I/F 3501 has received 32-pixelimage data, which is a data transfer unit for transfer to the pagememory 300, the scanner I/F 3501 outputs a transfer request to the PDRAMcontrol unit 36. In this case, in sync with a data transfer permissionsignal that is output to the PDRAM control unit 36, the scanner I/F 3501outputs the image data and an address, which is generated by the addressgeneration channel AGC (ch0) 3520 associated with the scanner transferchannel, to the PDRAM control unit 36.

The PDRAM control unit 36 mediates between transfer requests from therespective transfer channels and determines a transfer permissionchannel on the basis of an order of priority, such as round-robin. Inthe case of a write process from the transfer channel to the page memory300, the PDRAM control unit 36 first outputs a transfer permissionsignal to the transfer channel that is permitted to execute transfer,and receives the image data and address that are transferred from thetransfer channel in sync with the transfer permission signal.Subsequently, the PDRAM control unit 36 converts the input address to anaddress corresponding to the page memory 300, and generates a controlsignal corresponding to the page memory 300, thus writing the input datain an area corresponding to the address.

Each of the AGC (ch0) 3520, AGC (ch1) 3521, AGC (ch2) 3522, AGC (ch3)3523, AGC (ch4) 3524 and AGC (ch5) 3525 of the address generator 39 cangenerate a two-dimensional address corresponding to an original or apaper sheet, and is constituted by a main-scan address counter and asub-scan address counter (not shown).

The main-scan address counter counts up each time the access of theassociated transfer channel is permitted by the PDRAM control unit 36and the access is completed. When the main-scan address counter reachesa preset value of the original or paper sheet, the sub-scan addresscounter counts up and the main-scan address counter is cleared.

The above process is repeated, and when both the main-scan addresscounter and sub-scan address counter reach the preset value of theoriginal or paper sheet, transfer for one page is completed. Thereby,the main-scan address counter and sub-scan address counter are cleared.At the same time, the completion of access of one page is told to thesystem CPU 10 (page memory completion interrupt signal).

As a result, the image data that is read by the scanner sub-system 2 isstored in the page memory 300.

Next, a compression process for compressing image data that is read isdescribed.

The compression (input) channel 3502 responds to an input request fromthe compression process unit 3530 and outputs a request to the PDRAMcontrol unit 36. The compression (input) channel 3502 reads out imagedata from the page memory 300 and delivers it to the compression processunit 3530.

At this time, the setting of the AGC (ch1) 3521 that is used in theaddress generator 39 is the same as the setting of the AGC (ch0) 3520that is used for the image data input from the scanner sub-system 2.Thus, the image data that is transferred from the scanner sub-system 2and stored is compressed by the compression process unit 3530.

If the compressed data is outputtable, the compression process unit 3530outputs a data output request to the compression (output) channel 3503.The outputtable state, in this context, is a state in which compresseddata of a unit (32 bits) that can be written in the page memory 300 ispresent. The compression (output) channel 3503 writes the data in thepage memory 300 in the same manner as the scanner I/F 3501.

Each of the FIFO (ch1-A) 3528, FIFO (ch1-B) 3529, FIFO (ch0-A) 3526 andFIFO (ch0-B) 3527 of the address generator 39 is a one-dimensionaladdress generation channel and is constituted by a register and a loopcounter (not shown). The register sets an initial address and a finaladdress. The loop counter counts up the address from the initial addresseach time access is executed. When the final address is reached, theinitial address is loaded and count-up is started from the initialaddress once again.

The FIFO (ch1-A) 3528 and FIFO (ch1-B) 3529 constitute a pair, and theFIFO (ch0-A) 3526 and FIFO (ch0-B) 3527 constitute another pair. Thus, a2-channel (ch0, ch1) FIFO counter operation is executed.

The FIFO counter operation is described. Assume now that as regards thechannel ch0, the FIFO (ch0-A) 3526 executes write in the page memory 300and the FIFO (ch0-B) 3527 executes read-out from the page memory 300. Inthis case, in order to prevent the read-out from the page memory 300from outpacing the write in the page memory 300, the read-out access iscaused to wait when the counter value of the FIFO (ch0-B) 3527 hasbecome equal to the counter value of the FIFO (ch0-A) 3526.

In addition, the write FIFO (ch0-A) 3526 monitors a difference betweenboth counter values. If the difference between the counter values isequal to (final address-initial address), the write-side FIFO (ch0-A)3526 would overwrite and erase data before the read-out-side FIFO(ch0-B) 3527 executes data read-out. In order to avoid this, the requestby the write FIFO (ch0-A) 3526 is caused to stand by.

Thereby, the read-out FIFO (ch0-B) 3527 can read out only the image datathat is compressed by the compression process unit 3530.

The HDD transfer (ch0) 3504 and HOD transfer (ch1) 3506 function asinterfaces for data transfer between the HDD 830 and page memory 300. Ifthe HDD transfer (ch0) 3504 is in the data inputtable state, it outputsa transfer request and receives compressed data from the page memory300.

The IDE controller 800 acquires a control right of the system bus 9, andretrieves data from the HDD transfer (ch0) 3504 via the system bus 9 andwrites it in the HDD 830. The IDE controller 800 repeats this control.If the compression process for one page is completed, the processoperation is finished.

The decompression print operation is performed in an order reverse tothe scan compression operation.

To start with, the IDE controller 800 reads out the associatedcompressed image data from the HDD 830.

The IDE controller 800 outputs a transfer request to the system CPU 10so as to acquire the system bus 9.

The system bus controller 106 in the system CPU 10 mediates betweentransfer requests from individual devices on the system bus 9. When theturn of the IDE controller 800 has come, the IDE controller 800 ispermitted to execute transfer.

While the transfer by the IDE controller 800 is being permitted, the IDEcontroller 800 outputs the compressed data to the HDD transfer (ch1)3506 via the system bus 9.

If the HDD transfer (ch1) 3506 is in the data inputtable state, the IDEcontroller 800 receives data from the HDD 830 in accordance with arequest from the IDE controller 800. If the data that is input by theabove process is present in the HDD transfer (ch1) 3506, the HDDtransfer (ch1) 3506 outputs a transfer request to the PDRAM control unit36 and writes data in the page memory 300.

If the decompression (input) channel 3507 can take in data in thechannel, it outputs a request to the PDRAM control unit 36, reads outthe compressed data that is stored in the page memory 300 from the HDD830, and transfers the compressed data to the decompression process unit3531.

The decompression process unit 3531 decompresses the compressed dataaccording to a predetermined algorithm. If the decompressed data isoutputtable, the decompression process unit 3531 outputs a request tothe decompression (output) channel 3508. The decompression (output)channel 3508 receives the decompressed data, outputs a request to thePDRAM control unit 36, and writes the decompressed data in the pagememory 300.

The above-described process is repeated until the decompression processfor one page is completed.

If a rotation print instruction is not generated, the printer I/F 3509reads out image data from the print area of the page memory 300, usingthe AGC (ch2) 3522, and outputs the image data to the printer sub-system4 in sync with a sync signal that is output from the printer sub-system4. If a rotation print request is generated, the printer I/F 3509 readsout image data from the print area of the page memory 300, using the AGC(ch2) 3522, and subjects the image data to a rotation process in therotation process unit 3532 and outputs the resultant image data to theprinter sub-system 4 in sync with a sync signal that is output from theprinter sub-system 4.

The panel CPU 74 periodically checks the touch panel 71 and keys 72 fora key input through the control panel 7. If the panel CPU 74 detectsdepression of a key, the panel CPU 74 transmits a code, whichcorresponds to the depressed key, to the system CPU 10 via a serial I/F1100.

The SIO 105 in the system CPU 10 receives the transmitted code data, andinforms the CPU core 100 about the reception of the code via theinterrupt controller 104.

The CPU core 100 reads out the received data through the SIO 105,thereby recognizing the pressed key.

Next, the initializing operation in the present embodiment with theabove-described structure is described with reference to aninitialization sequence of FIG. 5.

In FIG. 5, it is assumed that the main control unit is the system CPU 10and the sub-control unit is the scanner CPU 203. The sub-control unitmay also be the printer CPU 43 or the panel CPU 74, which is initializedlike the scanner CPU 203, as described below.

When power is switched on, the system CPU 10 and scanner CPU 203 are inthe reset state. After a time following the switch-on, the reset stateis ended and the system CPU 10 and scanner CPU 203 execute individualinitializing processes.

The scanner CPU 203 sends an initialization command request to thesystem CPU 10 (ST1).

Upon receiving the initialization command request from the scanner CPU203, the system CPU 10 sends an initialization command to the scannerCPU 203 (ST2).

The scanner CPU 203, which has received the initialization command,executes an initializing process. When the initialization is completed,the scanner CPU 203 informs the system CPU 10 of the completion ofinitialization (ST3).

After the system CPU 10 is informed of the completion of initializationfrom all the sub-control units (including the printer CPU 43 and panelCPU 74 in this embodiment), the system CPU 10 instructs the LCD 70 todisplay “Ready” and enters the standby state.

Assume now that noise is input to the scanner CPU 203 and the scannerCPU 203 is reset.

The scanner CPU 203 sends an initialization command request to thesystem CPU 10 (ST4).

When the system CPU 10 receives the initialization command request fromthe scanner CPU 203 at a time other than the time immediately after theswitch-on, the system CPU 10 determines that the scanner CPU 203 iserroneously reset, and sends an initialization command to the scannerCPU 203 once again (ST5).

The scanner CPU 203, which has received the initialization command,executes an initializing process. When the initialization is completed,the scanner CPU 203 informs the system CPU 10 of the completion ofinitialization (ST6).

After the system CPU 10 is informed of the completion of initializationfrom the scanner CPU 203, the system CPU 10 sends a command other thanthe initialization command (ST7).

If the system CPU 10 receives an initialization command request from thescanner CPU 203 while a non-completed job is being executed, the systemCPU 10 re-sends an initialization command. Upon receiving information onthe completion of initialization, the system CPU 10 instructsre-execution of the non-completed job from the beginning. The samecontrol is executed for the printer CPU 43 and printer CPU 74.

As has been described above, according to the embodiment of the presentinvention, the sub-control unit sends an initialization command requestto the main control unit, and then the main control unit sends aninitialization command to the sub-control unit. Therefore, mismatchingof control can be prevented.

For example, even in the case where the sub-control unit is reset dueto, for instance, noise, the main control unit recognizes that thesub-control unit requires initialization, on the basis of aninitialization command request that is sent from the reset sub-controlunit, and can exactly initialize the sub-control unit.

Additional advantages and modifications will readily occur to thoseskilled in the art. Therefore, the invention in its broader aspects isnot limited to the specific details and representative embodiments shownand described herein. Accordingly, various modifications may be madewithout departing from the spirit or scope of the general inventiveconcept as defined by the appended claims and their equivalents.

1. An image forming apparatus that reads an image on an original andforms an image, comprising: a plurality of sub-control means forcontrolling a plurality of units that constitute the apparatus; and maincontrol means for controlling said plurality of sub-control means andcontrolling an initialization command to the sub-control means on thebasis of an initialization command request from each of the sub-controlmeans.
 2. The image forming apparatus according to claim 1, wherein saidplurality of sub-control means comprise image input control means forcontrolling image input means for inputting an image, image outputcontrol means for controlling image output means for outputting an imageusing image data, and panel control means for controlling a controlpanel that inputs an image formation condition and displays a state ofthe apparatus.
 3. The image forming apparatus according to claim 1,wherein the main control means controls initialization commands forimage input control means, image output control means and panel controlmeans on the basis of initialization command requests from the imageinput control means, the image output control means and the panelcontrol means that serve as said plurality of sub-control means.
 4. Animage forming apparatus that reads an image on an original and forms animage, comprising: a plurality of sub-CPUs that controls a plurality ofunits that constitute the apparatus; and a main CPU that controls saidplurality of sub-CPUs and controls an initialization command to thesub-CPUs on the basis of an initialization command request from each ofthe sub-CPUs.
 5. The image forming apparatus according to claim 4,wherein said plurality of sub-CPUs comprise a scanner CPU that controlsa scanner sub-system that inputs an image, a printer CPU that controls aprinter sub-system that outputs an image using image data, and a panelCPU that controls a control panel that inputs an image formationcondition and displays a state of the apparatus.
 6. The image formingapparatus according to claim 4, wherein the main CPU controlsinitialization commands for a scanner CPU, a printer CPU and a panel CPUon the basis of initialization command requests from the scanner CPU,the printer CPU and the panel CPU that serve as said plurality ofsub-CPUs.
 7. An image forming method for an image forming apparatus thatreads an image on an original and forms an image, comprising: providingsingle main control means for executing an overall control of theapparatus, and a plurality of sub-control means for controlling aplurality of units that constitute the apparatus in accordance with aninstruction from the main control means; and controlling aninitialization command to the sub-control means on the basis of aninitialization command request from each of the sub-control means.
 8. Animage forming method for an image forming apparatus that reads an imageon an original and forms an image, comprising: providing image inputmeans including an image input control unit that controls an imageinput; providing storage means for storing image data that is input bythe image input means; providing image output means including an imageoutput control unit that controls an image output using the image datathat is stored in the storage means; providing input display meansincluding a panel control unit that executes a control to input an imageformation condition and to display a state of the apparatus; providing amain control unit that controls the image input means, the storagemeans, the image output means and the input display means; and causingthe main control unit to control initialization commands for the imageinput control means, the image output control means and the panelcontrol means on the basis of initialization command requests from theimage input control means, the image output control means and the panelcontrol means.
 9. An image forming method for an image forming apparatusthat reads an image on an original and forms an image, comprising:providing a system CPU that executes an overall control of theapparatus, and a plurality of sub-CPUs that control a plurality of unitsthat constitute the apparatus in accordance with an instruction from thesystem CPU; and causing the system CPU to control an initializationcommand to the sub-CPU on the basis of an initialization command requestfrom each of the sub-CPUs.
 10. An image forming method for an imageforming apparatus that reads an image on an original and forms an image,comprising: providing a scanner sub-system including a scanner CPU thatcontrols an image input; providing a memory that stores image data whichis input by the scanner sub-system; providing a printer sub-systemincluding a printer CPU that controls an image output using the imagedata that is stored in the memory; providing a control panel including apanel CPU that executes a control to input an image formation conditionand to display a state of the apparatus; providing a system CPU thatcontrols the scanner sub-system, the memory, the printer sub-system andthe control panel; and causing the system CPU to control initializationcommands for the scanner CPU, the printer CPU and the panel CPU on thebasis of initialization command requests from the scanner CPU, theprinter CPU and the panel CPU.